python 文件目录操作

1. 判断文件是否存在

import os
path = r"C:\1.txt"
print(os.path.exists(path))

2. 遍历目录

import os

dirname = r"C:\output"

for filename in os.listdir(dirname):
    filepath = os.path.join(dirname, filename)
    print('=' * 60)
    print('文件名: ', filename)
    print('文件路径：', filepath)

    # 可以继续对文件做一些IO操作
    with open(filepath, 'r', encoding='utf-8') as f:
        pass

3. 文件的打开和关闭

方式1

filepath = r"C:\1.txt"
f = open(filepath, 'r', encoding='utf-8')  # 打开文件
# TODO
f.close()  # 关闭文件

方式2：使用with语句，执行完后会自动关闭文件

filepath = r"C:\1.txt"
with open(filepath, 'r', encoding='utf-8') as f:
    pass

4. 读取文本文件

f.read() 一次读取所有文本（读到EOF为止）

filepath = r"C:\1.txt"
with open(filepath, 'r', encoding='utf-8') as f:
    # 一次读完所有文本
    text = f.read()
    # 按行遍历
    for line in text.split('\n'):
        print(line)

for line in f 迭代一行一行读取，适用于读取大文件，可节省内存

filepath = r"C:\1.txt"
with open(filepath, 'r', encoding='utf-8') as f:
    # 一行一行读取
    for line in f:
        line = line.strip('\n')  # 去掉结尾的换行符
        print(line)

f.readline() 读取1行

filepath = r"C:\1.txt"
with open(filepath, 'r', encoding='utf-8') as f:
    # 读取1行
    print(f.readline())
    # 再读取1行
    print(f.readline())

f.readlines() -> List[str] 读取所有行

filepath = r"C:\1.txt"
with open(filepath, 'r', encoding='utf-8') as f:
    for line in f.readlines():
        line = line.strip('\n')  # 去掉'\n'
        print(line)

5. 写文本